By the 32nd and final day of his libel trial, David Irving was tired from the strain of representing himself in court.

His exhaustion helped to undermine his claim that he was a seeker of historical truth rather than a Hitler worshipper when, at a weary moment, he mistakenly addressed the judge as Mein Führer.

Irving had gone to the high court in London claiming that he was suing Penguin books and Professor Deborah Lipstadt to defend free speech and the right of historians to dissent from the mainstream view about the Holocaust.

In fact, money and rehabilitating his foundering career may have been Irving's real motive for suing.

The Guardian has established that Irving was in huge financial difficulty before the trial. He had taken out five mortgages on his flat off Grosvenor Square in London worth £750,000. Records lodged with the land registry show that two of his creditors had filed bankruptcy petitions against him, which were not followed up.

For Irving, 62, this also was a vanity libel trial, a chance to use the high court as a platform for his extreme views. Increasingly, he had been marginalised from the mainstream and confined to fringe neo-Nazi audiences.

Before the verdict, Irving told the Guardian that whatever the outcome: "My reputation as a historian has been greatly enhanced." He took pride from holding his own in court without the help of a defence barrister.

But a once glittering writing career, from which he earned up to £100,000 a year, was in severe decline. The doors of reputable publishing houses were closed to him as concerns about his integrity grew more acute.

In spring 1996, his American publisher, St Martin's Press, pulled out of a deal to publish his biography of Goebbels. That autumn, three years after the publication of Deborah Lipstadt's book Denying the Holocaust; the growing assault on truth and memory, he issued a writ for libel.

Irving saw her book and its charge that he was a Holocaust denier as the climax of an international, Jewish-inspired and long-running conspiracy against him that threatened his livelihood.

Lipstadt, 53, professor of Jewish and Holocaust studies at Emory university in Atlanta, Georgia, was determined to fight the case: "It became a personal quest for the preservation of truth and memory."

Irving's defeat was far from a foregone conclusion. The burden was on Penguin books and Lipstadt to prove their charges that Irving had wilfully distorted history to suit his fascist views.

Their counsel, Richard Rampton QC, staked out the uncompromising ground on which they would stand or fall on the first day.

"Mr Irving calls himself a historian. The truth is, however, that he is not a historian at all, but a falsifier of history. To put it bluntly, he is a liar."

The decision by Penguin and Lipstadt to plead justification, namely that the charges against Irving in her book were true, was not only a vastly expensive business but also a mammoth academic task.

Four years of research unearthed 30 examples of falsifications of history by Irving. It was the sheer weight of these and the consistent pattern they formed that won the day for Penguin and Lipstadt.

The method behind Irving's deceptions were complex, the effects significant.

The defence spent £80,000 on a 700-page report on Irving's historical methods from Richard Evans, professor of modern history at Cambridge university and an expert on the writing of history.

Prof Evans, who was paid £750 a day, and two PhD students spent two years combing through Irving's work. His report, which was submitted to the judge, shows his shock at the scale of deceptions he found:

"Penetrating beneath the confident surface of his prose quickly revealed a mass of distortion and manipulation ... so tangled that detailing it sometimes took up many more words than Irving's original account.

"A similar knotted web of distortions, suppressions and manipulations become evident in every single instance which we examined.

"I was not prepared for the sheer depths of duplicity which I encountered in Irving's treatment of the historical sources, nor for the way in which this dishonesty permeated his entire written and spoken output."

Both sides agreed to dispense with a jury because of the complexity of the evidence, leaving the judge, Charles Gray, adjudicating over one of the most emotive trials in memory.

The first sign of David Irving's Hitler worship came early, his twin brother Nicholas revealed. Recalling an incident in 1944 after a German bombing raid on Essex, he told an interviewer: "We were only six years old, it was 1944. There were doodlebugs, windows were blown out and houses had been damaged.

"Suddenly, David said: 'We have to say something.' So he went up to them, did a Nazi salute and said 'Heil Hitler'."

Irving dropped out of a science degree after his first book, The Destruction of Dresden, was published in 1963. His lack of formal training as a historian did not stop him writing 30 books.

The first clear sign that his apparent quest for historical truth seemed to be hiding an attempt to rehabilitate Hitler came in his 1977 bestseller, Hitler's war.

In the book Irving claimed Hitler had not ordered the extermination of the Jews and had even intervened to stop the murder of Jews. This, said Irving, was based on documents detailing communications between top German military leaders.

The court heard that one document referred to an order not to liquidate one trainload of 1,000 Jews sent from Germany to Latvia in November 1941.

Irving, through mistranslating the document, had falsely portrayed it as an order from Hitler to halt all such killings.

Before the trial, Irving claimed that the shooting of up to 1,500,000 Jews on Germany's eastern border with Russia, was not systematic but a series of random acts of which Hitler was unaware.

During the trial, evidence was produced which forced Irving to concede Hitler had indeed sanctioned them.

One such piece of evidence was an order on August 1 1941 to a mobile killing unit, the Einsatzgruppen, which said Hitler would be getting continuous reports about their shootings.

This evidence had been known to Irving since 1982. A copy of the order was contained in a book found in Irving's study, in which he had written notes in the margin, suggesting he had read it.

Gas chambers

Irving later admitted that a report in December 1942 detailing the execution of 363,211 Jews in South Russia, Ukraine and Bialystok "was in all probability shown to Hitler."

For the second edition of Hitler's War in 1991, Irving had expunged all references to the Holocaust.

Irving's position in court was that the Nazis may have killed between 1m-4m people, but that it was not systematic and did not involve gas chambers.

"He posed as a thoughtful intellectual, burrowing away with original source documents to try to seek the truth about the Holocaust.

But a series of viciously anti-semitic speeches he had made to neo-Nazi audiences, which suggested he had denied the Holocaust, put paid to that image.

The judge heard extracts from a 1991 speech given by Irving in Calgary, Canada, in which he rubbished the idea that the Auschwitz camp existed to murder Jews. "It's baloney. It's a legend.

"Once we admit the fact that it was a brutal slave labour camp and large numbers of people did die, as large numbers of innocent people died elsewhere in the war, why believe the rest of the baloney?

"Tasteless. I say quite tastelessly, in fact, that more women died on the back seat of Edward Kennedy's car at Chappaquiddick than ever died in a gas chamber in Auschwitz.

"Oh, you think that's tasteless, how about this? There are so many Auschwitz survivors going around, in fact the number increases as the years go past, which is biologically very odd to say the least.

"I'm going to form an association of Auschwitz survivors, survivors of the Holocaust and other liars, or the ASSHOLS."

This trial turned on the death camp at Auschwitz. Despite evidence to the contrary, Irving clung to his view it was no more than a "brutal slave labour camp".

The court heard how Irving misinterpreted documents involving the testimony of an Auschwitz survivor at the Nuremburg trials, a French woman called Marie-Claude Vaillant Couturier.

Irving twisted the private diaries of Judge Francis Biddle, who presided over the trial where Vaillant Couturier testified, to try to rubbish her evidence.

In a speech, Irving claimed that Biddle's notes of the trial, which he unearthed in an American university library, showed he disbelieved her evidence.

Irving told an audience that Biddle wrote: "I don't believe a word of what she's saying, I think she's a bloody liar."

Vaillant Couturier's evidence had set out the horror of the death camp. She had been a member of the French national assembly and was sent to Auschwitz in 1943. There she testified to seeing beatings, forced sterilisations and castrations and gas chambers.

In fact, Biddle doubted only one small section of her testimony. According to Irving's own notes of the judge's diary, Biddle records her as saying: "House of prostitution for SS selected young women as they were washing for maids. All camps used the same system."

After this remark, Biddle, in brackets writes, "this I doubt", namely that the same system was used at every SS camp.

Irving dismissed the witnesses to systematic extermination at Auschwitz as wrong or lying. He claimed 100,000 people had died there, the same number as at Dresden, and that was through disease, overwork and some shootings.

Irving's revisionist views on Auschwitz were prompted by a report written by American extremist Frederick Leuchter in 1989.

In the report Leuchter claimed that samples of concrete taken from the surviving walls at Auschwitz's gas chambers contained quantities of hydrogen cyanide that were too low to kill human beings, and thus suggested the chambers were for delousing.

But the truth was quite the reverse. The real amount of hydrogen cyanide needed to kill humans is 22 times lower than that needed to kill lice.

Irving wrote the foreword to the Leuchter report. During the trial he was forced to admit it was riddled with errors.

In court, Irving rejected the label of being a Holocaust denier, saying he did not question that it had happened, but merely queried the "means, the scale, the dates and other minutiae."

The court heard evidence that Irving was an anti-semite and racist. He displayed his prejudice in front of his young daughter, singing the ditty: "I am a baby Aryan/Not Jewish or sectarian/ I have no plans to marry an/Ape or Rastafarian."

Irving consorted with the far right, addressing meetings of the Hitler-worshipping British National Party, the German neo-Nazi DVU party and extreme right National Alliance in the US.

Germany got so fed up with Irving that it eventually banned him from entering, as did Canada and Australia.

Perhaps the biggest insight into his deeper motivation comes not from the libel case, but from the opening line of his introduction to the new edition of Hitler's War, posted on his website:

"To historians is granted a talent that even the gods are denied - to alter what has already happened."